[LEAPSECS] the inescapability of feedback

[Rob Seaman]

Steve Allen wrote:


> Someone please tell me again why the zoneinfo files would need 10  

> years of advance notice if they were to absorb responsibility for  

> leap seconds.


Rather the opposite.  Nobody would object if the schedule for  
announcing leapseconds could be extended to 10 years (all else being  
equal).  On the other hand, world governments would balk at any  
attempt to limit their sovereignty by requiring a 10 year lag before  
timezone and DST changes could take effect.  The scientific community  
is clearly more accommodating here than the political community.

A parable:  NOAO has facilities in southern Arizona and northern  
Chile.  Neither Chile nor Arizona underwent a daylight saving time  
change on March 9, and yet both encountered DST goofs on that day.   
Arizona doesn't observe DST (the last thing we need to save is  
daylight), and the government of Chile decided to extend DST for the  
southern summer for a few extra weeks this year.

Several "atomic" wall clocks reset themselves in Arizona.  They  
actually fell back, rather than forward (?!?) - best guess is that  
they had been set to Pacific time + DST and the DST flag was  
interpreted as a toggle (thus shifting to standard time).  Sounds  
pretty lame, but that's what the clocks did.

A large number of NTP synced unix clocks (various flavors) in Chile  
automatically moved back to standard time since the configurations  
weren't updated in a timely fashion.

One would expect the stress of rising energy prices combined with the  
rather contradictory logic of DST regarding saving energy to only  
result in additional short notice government timekeeping decisions.   
This suggests that there is a requirement for an improved  
infrastructure for managing timezone information, and not to allow the  
infrastructure to wither.  The only alternative is chaos.

Poul-Henning Kamp wrote:


> Because stupid handling of timezones is something politicians you  

> vote for do, and consequently there is a feedback loop that can  

> discourage such behaviour.

>

> Leapseconds are mandated by a bunch of scientists who are not  

> accountable for anybody if they suddenly decide to issue leapseconds  

> with 1 month notice.



It is a neat trick to accuse one party (scientists) with the crime of  
the other (politicians).

Scientists are much more accountable through funding agencies, etc.,  
than any government entity.  Note also, of course, that not all  
stakeholders have the opportunity to vote for their politicians.  And  
what is the ITU but a mechanism for holding a "bunch of scientists"  
accountable?  With absolutely zero irony, this mailing list can be  
described as such a feedback mechanism.

The ultimate feedback loops for timekeeping are the natural rhythms  
that govern our civil institutions and technical infrastructure.  We  
(scientists or politicians) are not free to willy-nilly redefine the  
clock and the calendar.  In particular, the clock is a subdivision of  
the calendar.  The ITU initiative refers to leap seconds, but it is  
really an attempt to change the definition of the "day".

I've gotta say that I'm perplexed at your reception of Steve's  
suggestion.  Your own idea (correct me if I'm wrong) is that the  
secular clock drift due to embargoed leap seconds will be accommodated  
via local adjustments to the standard timezone system.  Steve has  
simply fleshed out the details for one such mechanism to manage all  
the local adjustments coherently.

If leap seconds aren't going to carry the weight of civil time  
anymore, than this weight will fall somewhere else.  If it falls onto  
the system of timezones, then the timezones will have to be reinforced  
to bear the weight.  If not via zoneinfo, then how?

John Hein wrote:


> For those applications that do care about local time, there are  

> other forums for discussing this class of problem.  It's certainly a  

> real issue for some, but is separable from the issues associated  

> with leap seconds.


It is precisely that UTC is kept stationary with respect to mean solar  
time that permits local timezone issues like DST to be separable from  
UTC as you describe.

Rob Seaman
National Optical Astronomy Observatory